The use of solidification technology and solid block detergents in institutional and industrial operations was pioneered in the SOLID POWER® brand technology claimed in Fernholz et al., U.S. Reissue Pat. Nos. 32,762 and 32,818. Additionally, sodium carbonate hydrate cast solid products using substantially hydrated sodium carbonate materials was disclosed in Heile et al., U.S. Pat. Nos. 4,595,520 and 4,680,134.
In more recent years, attention has been directed to producing highly effective detergent materials from less caustic materials such as soda ash, also known as sodium carbonate. Early work in developing the sodium carbonate based detergents found that sodium carbonate hydrate-based materials often swelled, (i.e., were dimensionally unstable) after solidification. Such swelling can interfere with packaging, dispensing, and use. The dimensional instability of the solid materials relates to the unstable nature of various hydrate forms prepared in manufacturing the sodium carbonate solid materials. Early products made with hydrated sodium carbonate were typically comprised of anhydrous, a one mole hydrate, a seven mole hydrate, a ten mole hydrate or more mixtures thereof. However, after the product had been manufactured and stored at ambient temperatures, the hydration state of the initial product was found to shift between hydrate forms, e.g., one, seven, and ten mole hydrates, resulting in dimensional instability of the block chemicals. In these conventional solid form compositions, changes in water content and temperature lead to structural and dimensional change, which may lead to a failure of the solid form, resulting in problems such as the inability of the solid form to fit into dispensers for use.
Additionally, conventional solid alkaline detergents, particularly those intended for institutional and commercial use, generally require phosphates in their compositions. The phosphates typically serve multiple purposes in the compositions, for example, to control the rate of solidification, to remove and suspend soils, and as an effective hardness sequestrant. U.S. Pat. Nos. 6,258,765, 6,156,715, 6,150,324, and 6,177,392, disclose that a solid block functional material could be made using a binding agent that includes a carbonate salt, an organic acetate, such as an aminocarboxylate, or phosphonate component and water. Further work has recently been directed to replacing phosphorous-containing compounds in detergents. One replacement is nitrilotriacetic acid (NTA)-containing aminocarboxylate components, which can be used as a binding agent and/or hardness sequestrant. However, the use of NTA has also been curtailed.
There is an ongoing need to provide alternative solidification technologies which are phosphorous-free and/or NTA-free. However, the lack of predictability in the solidification process and the lack of predictability of dimensional stability in solid form compositions have hampered efforts to successfully replace phosphorous and/or NTA-containing components with more environmentally friendly substitutes.